Threading cables through ducts



INVENTOR M A TTO'R/VE Y March 29, 1932.

G. K. JESSUP THREADING CABLES THROUGH DUCTS 7 Filed Oct. 22, 1927 Y Q GEORGE/KZ/EJSUH Fatented'Mar. 29; 1932' entree STATES} GEORGE K. JEsstrr, or GREENWIGH, ooivnnctrioiir', itssrenonfiiimnsnn essfdna. 1

MENTS, T METROPOLITAN nnvroncoaronnrron, A CORPORATION or-nnwfjonx THREADING oABnEs 'rnnouer'ifnucrs V 7 Application filed October 22,1927. Serial no. sashes.

The invention provides a method and a device of very simple construction by which a cord can be threaded through an under ground duct from one manhole to another 1n.

The accompanying drawings illustrate em bodiments of the invention.

Fig. 1 is a perspective partly insection ot a bank of ducts between two manholes;

Fig. 2 is a. vertical section of a lead-in in place;

Fig. 3 is an end View ofthe same. K In Fig. 1 two straightducts l are shown in section extending between, manholes 2. A lead-in 3 has a cord 4 attachedto its rear end, trailing through a hole in the lower part of a plug 5 which is inserted in the left end of the duct. An air hose 6 connected with a source of compressed air has a nozzle 7 passing through a hole in the center of the plug and is provided with a cock 8'.

Initially the lead-in 3 is placed in the duct with its rear end at the manhole, the cord is threaded through the plug and'fastened to the lead-in and the plug introduced into the end of the duct. The nozzle is then pushed into the central hole in the plug and the cock 8 opened. 'The air propels the lead-in through the duct'and into the tar manhole very quickly, in a fraction of a second in one test.

attached to the cord and pulled through the duct. Where a light cable and a: straight to pull a heavier cord or rope through the duct, and the rope used to pull a heavy cable through.

To secure ease and quickness of operation the leadin is made very light. The example in Fig. 2 has its body portion madeof a thin cylindrical shell 9 of copper with a pointed or rounded forward endlO and with a con- 7 cave plate or sealing disc 11 soldered to its rear end. To this in turn is soldereda cone 12 to which are soldered rods 13 converging The plug is then removed and the cable attachment of, the cord, rope or cable The entire device is light enough .toj float' on any water which maybe" in the duct. 1 It approximately fits the duct, leavin'gclearance enough i to insure easy. movement under; the press ire of airbehindit. It may be-made so light as o b pr p l imp d y by eai even.-without the plug 5 in the rear @ndof l the duct.

It is, ssential that any substantial-pressure I of airbe built up behind the lead-in ,The 7 opening in theplug 5 through which the. cord t runs is large enough to permit memoirs-- ment of the cord and also to permit the es--* cape of much of the airblown into the duct,

and the space around -thepiston, as shown in Figs. 2 and 3, is made so great (00 ensure perfect freedom of travel) that alarge quantity of air can escape from the rear to the "front.of'the-devicej Nevertheless; the whole device is so light that it canbe forcedeasily andvery quickly through the duct by a cure I 5 rent of air. I am aware thatrdevices for .achi eving Similar purposes have been: made .with .expansible parts to secure a olosefit and permit the accumulation of air or water pressure behindthem to force themrlike a tight piston through the pipe 'or duct. Fin suchgdevices there has been no sub'stan- But tial reason v for restricting the weight. The

carry them along regardless ofthe weight or the. frictional engagement with the tube.

j With my device it'isthe combination of particularly light weight and fixed cross-section fitting loosely within the duct which permits the very quick passage of the lead-in by the simpleexpedient of introducing a current of i have shown a. lead-in 15 of similar construction to that above described but having the L cylindrical-portion nearly orv entirely eliminated; that is with its converging front and rear portions united at theirbascs directly or approximately so. This shape is particularly designed for ducts which have a curve pressure behind themhas been sutficient to '.JI;-1.. i; 1,851,435

in their length which it would be difficult to force an elongated cylinder through.

' Various other shapes canbe-designedof;

the same'loose piston character designed to be propelled freely through. a duct by fluid.

pressure at the rear; V Vm ious'other modifications i'n'ay' be mde by thoseskilled in the art Withoutdeparting from, theinvention as defined .in the followf "inglelziiins 7 1. A lead-in forthreadingcahles through ducts comprising a piston of fixed crosssection fitting loosely-Within the duct and permitting the passage ofrair between it and r "the -ducq said piston being of such-light Weightjithfit itcan 'be forced-through the duct quiekly'b eurrenc 0f air "and in freesusi 2.-'A*-le'ad injfor threadingcebles through ductsfioinprising a piston foffixed cros's s'ecltion fitting' loosely Within the duct and-per mitting' the 'pas sage of ai'rbetwe'en it and "3 the duct, said piston being ofs'uc h-iight y Weightjthtt itczinbe forcedthrough the-duct quickly-by "a current of air and in free-"suspension in air, said piston' being hollow and "converging "at both ends and means for att tach ing a cord to said piston.

I 3. A th'od of pr'ope1ling* a lead-in 'lthi'ougha conduit which comprises floating V *seidleed-in Within; and out of Contact with; ftheinner' wzill' 'surfaice of said conduit by 3 mea'nsof-a moving layerof air thereb'etween iand-"crezitin-g e difference in pneumaticpres- V ,sureo -the opposite ends ofsaid 1efid in,"thfe pressure being lesstowards the direction of Y navel of saidlead-in.

" Q 4:A methodofpropelling a. lead-in "through -"a conduitiyhichcomprises moving a 1ayerofiair between the leed-sin'andthe in fnersurflceofsi-id conduit to floats'aidle'id- ,-in' ont' ofc0ntact with the walls-of said con-c I f'diiit 'iind forcingfiiir againstonefend' of sziid 'nify' iifarne." V r y .g RGE-' T UR 

